Effect of polysaccharides and water extract from Fructus tribuli on Growth of Lactobacillus brevis was studied by measuring the optical density at 600 nm and pH using commercial MRS broth as the control. The addition (mg/mL) of steroidal saponins was 0.10, 0.20, 0.30, 0.40 and 0.50 and the addition (%, v/v) of water extract was 1, 2, 3, 4 and 5. Results were as follows: The additions of polysaccharides and water extract had a significant promotion on the growth of Lactobacillus brevis. Lactobacillus brevis. The optimum concentrations of steroidal saponins and water extract were 0.40 mg/mL and 5%, respectively.